Improving the Coupling Capacitors for Better Tone Sounding

[ricardo]

Although there have been a lot of advances in capacitors, some of the silver mica caps are definitely worth looking into.

Guru Scott Wurcer investigated caps for LN stuff. I had some correspondence with him on the subject and I think he put some of this in his Linear Audio articles on condensor microphone amps.

He found Polystyrenes microphonic and Silver Micas introduced a strange noise. The best small caps were NPO/CGO ceramics. If the voltage / values / size fit, use them.

Tantalums and some of the uber Electrolytics also introduce noise at a very low level. If LN is your thing, use cheapo Aluminium Electrolytics and bias them properly.

 

[Matador]

The best small caps were NPO/CGO ceramics.

I recently swapped some NP0/C0G ceramic MLCC's into a Fender tremolo circuit, and along with LED biasing, it gives for rock stable tremolo frequency, from the start of the gig when the bar is cold, to 2am after 12 beers.

 

[soapfoot]

…but where’s the fun in that?

 

[opacheco]

Guru Scott Wurcer investigated caps for LN stuff. I had some correspondence with him on the subject and I think he put some of this in his Linear Audio articles on condensor microphone amps.

He found Polystyrenes microphonic and Silver Micas introduced a strange noise. The best small caps were NPO/CGO ceramics. If the voltage / values / size fit, use them.

Tantalums and some of the uber Electrolytics also introduce noise at a very low level. If LN is your thing, use cheapo Aluminium Electrolytics and bias them properly.

I never heard about the NPO/CGO ceramics capacitors at least with those names!; do you have more info about the Scott Gurcer study or investigation? Where I can find this investigation paper or notes?

Thanks a lot,
opacheco

 

[opacheco]

Use only capacitors hand carved from Unobtainium and solid BS by virgins !
If you send me US$100 in used bank notes, I'll send you a sample. You can just stick it to the chassis with BluTak to enjoy improved clarity and definition. No need to even solder it in.
No Confederate money please

Sorry what you talking about? I don’t understand nothing you say!

opacheco

 

[opacheco]

……most friends who used tube amps with those old mustard yellow colour Mullard capacitors stated that the amp sounded best after twenty minutes warm up. Technically those caps were not so temperature stable as modern MK types, so perhaps there was some kind of drift. But I think we all probably got used to the sound after 20 minutes...
most friends who used tube amps with those old mustard yellow colour Mullard capacitors stated that the amp sounded best after twenty minutes warm up. Technically those caps were not so temperature stable as modern MK types, so perhaps there was some kind of drift. But I think we all probably got used to the sound after 20 minutes...

ok, I will considering that too!
Thanks
opacheco

 

[JohnRoberts]

Sorry what you talking about? I don’t understand nothing you say!

opacheco

He's joking

JR

 

[opacheco]

He's joking

JR

 

[Newmarket]

He's joking

JR

"Joking without the G" ?
In memory of the late great BBC Radio DJ Steve Wright

 

[Cqwet Dbdfte]

Hi to everyone!

I am trying to improve the tone quality of this tube amplifier at maximum! and I would like to know what kind of coupling and dis-coupling capacitors can I use in order to achieve this superior sound quality, instance to the actuals Mica cheap capacitors used actually?

I have attached the schematic for your considerations and advices.

Thanks in advance!
opacheco

Lots of mythology runs thru capacitors.
"Tone" is very subjective, and good coupling caps should pass the lowest desired frequency and not leak any DC as to destroy the bias of the next tube.
You can EASILY measure leakage with a DVM: remove connection on low voltage side, measure voltage with the DVM, take the number of volts snd divide by 10,000,000.
The number should be very small.
Old caps can be leaky, giving unwanted surprises.
Replace as suggested with PP caps.
Paper in Oil, PIO, may have some dielectric absorption effect, maybe audible. Maybe OK?
As "tone" is not measurable hard to say.
Some PIO are shipped with metal shorting clamps to keep surprises to a minimum.
10kV 4uF is no joke.

 

[RCAguy]

Coupling capacitor distortion is relatively easy to reduce. Now with reduced-size audio-grade ‘lytics (even tantalums), just oversize so they have barely any voltage drop at the lowest frequency of interest, say 16Hz, then calculate for f3 of 1.6Hz.

The reason: Oversizing means no voltage drop at the lowest frequency of interest, so there can’t be any distortion imposed. - Douglas Self